Generally, a compressor is for compressing a fluid. The compressor can be divided into a rotation compressor, a reciprocating compressor and a scroll compressor, etc. according to fluid compression types.
In the rotation compressor, a rotational shaft rotates by receiving a driving force of a rotational motor, simultaneously an eccentric part combined with the rotational shaft performs an eccentric rotation in a cylindrical compression space of a cylinder, and accordingly gas is compressed.
In the scroll compressor, a rotational shaft rotates by receiving a driving force of a rotational motor, simultaneously a rotary scroll combined with the rotational shaft engaging with a fixed scroll performs a rotating motion, and accordingly gas is compressed.
In the reciprocating compressor, a rotational shaft rotates by receiving a driving force of a rotational motor, simultaneously a connecting rod combined with the rotational shaft converts the rotating motion into a linear reciprocating motion and transmits it to a piston, the piston performs the linear reciprocating motion in a cylinder, and accordingly gas is compressed.
In addition, in another type of the reciprocating compressor, a piston receiving a driving force of a reciprocating motor performs a linear reciprocating motion in a cylinder, and accordingly gas is compressed.
FIG. 1 illustrates a reciprocating compressor in accordance with the conventional art. As depicted in FIG. 1, the reciprocating compressor includes a container 100 having a suction pipe 10 in which gas is sucked; a frame unit installed inside the container 100; a reciprocating motor installed at the frame unit and generating a linear reciprocating driving force; a compression unit installed at the frame unit with a certain distance from the reciprocating motor, receiving the driving force of the reciprocating motor and compressing gas; a spring unit for elastically supporting the linear reciprocating driving force of the reciprocating motor; and a valve unit installed at the compression unit and opening/closing a compression space in which gas is compressed.
The container 100 is sealed to have a certain inner space, and the suction pipe 10 penetrates-combines with the container 100 so as to communicate with the container 100.
The reciprocating motor consists of an outer stator 310 installed at a rear frame 210 of the frame unit; an inner stator 320 inserted into the outer stator 310 with a certain interval; a wound coil 330 inserted into an open groove 311 formed at the outer stator 310; and a mover 340 inserted between the outer stator 310 and the inner stator 320 to perform a linear reciprocating motion.
And, a middle frame 220 is fixedly combined with a certain side of the reciprocating motor to face the rear frame 210.
The compression unit includes a cylinder 410 combined with a front frame 230 having a certain distance from the reciprocating motor and a piston 420 inserted into a compression space 411 of the cylinder 410 and connected to the mover 340 of the reciprocating motor.
And, in the front frame 230, a protrusive supporting portion 232 extended from a certain side of a plate portion 231 is formed so as to have a certain length, and a through hole 233 in which the cylinder 410 is inserted is formed at the supporting portion 232.
In the cylinder 410, the compression space 411 penetrates through a cylinder body 412 having a certain length. And, the cylinder 410 is inserted into the through hole 233 of the front frame 230.
Herein, the end surface of the supporting portion 232 of the front frame 230 is the same surface as the end surface of the cylinder body 412.
The piston 420 includes a body unit 421 having a certain length and a flange portion 422 extended from a certain side of the body unit 421 so as to have a certain size and connected to the mover 340.
In the piston 420, the flange portion 422 is combined with the mover 340, and the body unit 421 is inserted into he compression space 411 of the cylinder 410.
The spring unit includes a certain-shaped spring supporting portion 510 in which a certain side is combined with the flange portion 422 of the piston 420 or the mover 340 so as to place between the front frame 230 and the middle frame 220; and a spring 520 respectively placed at both sides of the spring supporting portion 510.
The valve unit includes a discharge cover 610 combined with the front frame 230 to cover the compression space 411 of the cylinder; a discharge valve 620 placed inside the discharge cover 610 and opening/closing the compression space 411 of the cylinder 410; a valve spring 630 for elastically supporting the discharge valve 620; and a suction valve 640 combined with the end of the piston 420 and opening/closing a suction channel 423 formed inside the piston 420.
Unexplained reference numeral 20 is a discharge pipe, 240 is a connecting member of the frame unit, and 341 is a permanent magnet.
The operation of the conventional reciprocating compressor will be described.
When power is applied to the reciprocating motor, a current flows onto the wound coil 330 of the reciprocating motor, a flux is formed between the outer stator 310 and the inner stator 320, by mutual operation of the flux between the outer stator 310 and the inner stator 320 with a flux by the permanent magnet 341 of the mover 340, the mover 340 performs a linear reciprocating motion.
The linear reciprocating driving force of the mover 340 is transmitted to the piston 420, and the piston 420 performs a linear reciprocating motion inside the cylinder compression space 411.
The spring unit stores, discharges the linear reciprocating power of the reciprocating motor as elastic energy and causes a resonance motion.
With the linear reciprocating motion of the piston 420 in the compression space 411 of the cylinder 410, the valve unit is operated, the gas sucked into the suction pipe 10 is sucked into the compression space 411 through the suction channel 423 of the piston 420, compressed discharged, herein, the gas is discharged to the outside through the discharge pipe 20 of the discharge cover 610.
In general, the compressor includes a cooling cycle apparatus and is installed to an air-conditioner, a refrigerator and a showcase, etc. In order to install the compressor to a system such as an air-conditioner, a refrigerator and a showcase, etc., the compressor has to have a simple structure and require a small installation space and operate stably.
In the meantime, unlike other compressors, in the reciprocating compressor, an output of the reciprocating motor as a driving power source is a linear reciprocating motion power, the piston 420 receives the linear reciprocating motion power of the reciprocating motor and performs the linear reciprocating motion in the compression space 411 to compress the gas, and accordingly constructing parts moving in the axial direction compactly is important object to simplify a structure of the compressor.
In the meantime, as depicted in FIG. 2, in a reciprocating compressor constructed by considering the above-mentioned object, in the linear reciprocating motion of the flange portion 422 of the piston (receiving the driving force of the reciprocating motor and performing the linear reciprocating motion in the compression space 411 of the cylinder), a distance between the inner stator 320 of the reciprocating motor respectively placed at both sides of the flange portion 422 and the front frame 230 corresponds to a reciprocating motion distance of the flange portion 422.
And, the flange portion 422 of the piston 420 is placed between the inner stator 320 and the front frame 230, a distance (a) between the end surface of the front frame 230 and the flange portion 422 is the same as a distance (b) between the inner stator 320 and the flange portion 422.
And, as depicted in FIG. 3, in the cylinder 410 in which the piston 420 is inserted and the front frame 230 of the frame unit in which the cylinder 410 is inserted, the end surface (c) of the cylinder 410 is placed on the same surface as the end surface (d) of the supporting portion 232.
In the above-mentioned construction, the piston 420 receives the linear reciprocating driving force of the reciprocating motor, sucks, compresses and discharges the gas while performing the linear reciprocating motion in the compression space 411 of the cylinder 410, however, by the compressed gas force in the compression space 411, the center of the reciprocating motion of the piston 420 may be moved from an initial position toward the reciprocating motor, due to that, the flange portion 422 of the piston 420 may collide against the inner stator 320 of the reciprocating motor during the linear reciprocating motion, and accordingly collision noise may occur and the operation may be unstable.
In addition, when the piston 420 performs the unstable reciprocating motion, the flange portion 422 of the piston 420 may collide against the end surface (d) of the supporting portion 232 of the front frame 230 and the end surface (C) of the piston 420, impact may be applied to the piston 420 and the front frame 230, and accordingly the assembly condition of the valve unit connected to the cylinder 410 may not be secured.